In vitro fertilization (IVF) has evolved significantly, with Preimplantation Genetic Testing for Monogenic disorders (PGT-M) now enabling the prevention of specific inherited genetic diseases in offspring. This advanced technique allows for the screening of embryos created through IVF for known genetic mutations, offering couples the opportunity to avoid passing on conditions such as thalassaemia, sickle cell disease, and certain hereditary cancers. While PGT-M represents a major breakthrough for families burdened by these monogenic disorders, it's important to note its limitations, as it cannot address multifactorial diseases influenced by a combination of genetic and environmental factors.

In vitro fertilization (IVF) has evolved significantly, with Preimplantation Genetic Testing for Monogenic disorders (PGT-M) now enabling the prevention of specific inherited genetic diseases in offspring. This advanced technique allows for the screening of embryos created through IVF for known genetic mutations, offering couples the opportunity to avoid passing on conditions such as thalassaemia, sickle cell disease, and certain hereditary cancers. While PGT-M represents a major breakthrough for families burdened by these monogenic disorders, it's important to note its limitations, as it cannot address multifactorial diseases influenced by a combination of genetic and environmental factors.

In vitro fertilization (IVF) has evolved significantly, with Preimplantation Genetic Testing for Monogenic disorders (PGT-M) now enabling the prevention of specific inherited genetic diseases in offspring. This advanced technique allows for the screening of embryos created through IVF for known genetic mutations, offering couples the opportunity to avoid passing on conditions such as thalassaemia, sickle cell disease, and certain hereditary cancers. While PGT-M represents a major breakthrough for families burdened by these monogenic disorders, it's important to note its limitations, as it cannot address multifactorial diseases influenced by a combination of genetic and environmental factors.

For decades, we have known IVF for a single promise, which is a positive pregnancy test. Today, that promise has quietly expanded. Ask fertility specialists what success looks like now, and most will say the same thing: it isn't just about conception anymore. It's more about the kind of life that follows it, as in today’s world, when almost everyone is carrying some or other disease, which is either due to their lifestyle or genetically inherited. IVF is the only way through which parents can free their child from these diseases by choosing IVF over natural birthing.

That is because of Preimplantation Genetic Testing for Monogenic disorders, or PGT-M. And for families who have watched an inherited illness move through generation after generation, it may be one of the more quietly significant advances in modern medicine.

How it actually works

During a standard IVF cycle, eggs are fertilised in the laboratory and allowed to develop for five to six days, until the embryo reaches what is known as the blastocyst stage — a cluster of a few hundred cells. At this point, embryologists carefully extract a handful of cells from the outer layer, the part that will eventually form the placenta, leaving the cells destined to become the baby untouched. The embryo is frozen, while the extracted cells are sent for genetic analysis.

If the family already carries a known disease-causing mutation, geneticists can check whether each embryo has inherited it. Only embryos free of that specific mutation are considered for transfer. It's a precise, almost surgical form of prevention, one that happens before pregnancy even begins, rather than the anxious wait for prenatal results that has defined this decision for previous generations.

Whose stories does this change

India has one of the world's highest burdens of inherited blood disorders, and thalassaemia and sickle cell disease are the ones against which PGT-M is most frequently used. But the list runs longer: spinal muscular atrophy, Duchenne muscular dystrophy, cystic fibrosis, haemophilia, Fragile X syndrome, Huntington's disease, and Tay-Sachs and Gaucher disease among them. More recently, it has extended to hereditary cancer syndromes like BRCA1 and BRCA2 mutations linked to breast and ovarian cancer, Lynch syndrome, which offered to families who have watched cancer recur across generations and wanted a different outcome for their own children.

Crucially, this isn't limited to couples who are visibly unwell. Many carriers of these mutations have no symptoms themselves. It's only when both partners in a couple happen to carry the same recessive gene, or one carries a dominant one, that the risk becomes real for their children. Expanded carrier screening before conception is increasingly uncovering these risks in couples with no family history at all, turning what used to be a discovery made mid-pregnancy into one made before it starts.

Where the science stops

It would be dishonest, though, to let the promise of PGT-M run further than the evidence allows. This is not a technology that can screen away diabetes, thyroid disorders, epilepsy in general, or heart disease. These are multifactorial conditions that are shaped by dozens of genes interacting with diet, environment and lifestyle, and no embryo test can isolate a single cause to select against. Even epilepsy, which sits somewhere in between, can only be addressed through PGT-M in the rare cases where a single gene mutation, such as in SCN1A, has already been identified in the family. For the vast majority of common health conditions Indian families worry about, PGT-M simply isn't the answer, and claiming otherwise does a disservice to the very couples trying to make informed decisions.

A quieter kind of hope

What PGT-M offers isn't a guarantee of a perfect child, nor an escape from illness altogether. It offers something narrower and, in some ways, more meaningful: a chance for families who have lived with a specific, identified genetic threat to stop it from repeating. For a couple who has already lost a child to a metabolic disorder or watched a parent's illness recur in a sibling, that narrower promise can still feel like an enormous one.

As the science matures, the conversation around IVF may keep shifting, as it started from a story about infertility to one about the prevention of genetic disorders in the next generation.

The author is the director of Obstetrics & Gynaecology at CK Birla Gurgaon.

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK. 

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